富水粉土粉砂地层基坑降水开挖引起渗流场和位移场变化分析  

Analysis on changes in seepage and displacement fields induced by descending excavation of foundation pits in water-rich chalky soil and silt formations

作　　者：焦雪洋 高鹏举 杨沫 丁建文[2] 刘雪源 Jiao Xueyang;Gao Pengju;Yang Mo;Ding Jianwen;Liu Xueyuan(China Construction Eighth Engineering Division Rail Transit Construction Co.,Ltd.,Nanjing 210023,China;School of Transportation,Southeast University,Nanjing 210096,China)

机构地区：[1]中建八局轨道交通建设有限公司,南京210023 [2]东南大学交通学院,南京210096

出　　处：《工程勘察》2025年第3期9-15,共7页Geotechnical Investigation & Surveying

基　　金：国家自然科学基金(52378330).

摘　　要：为了探究天津富水粉土粉砂地层中深基坑降水开挖引起的周边渗流场和位移场变化,以天津某地铁车站深基坑为工程背景,开展了坑内降水试验,并对开挖阶段坑外地下水位、基坑周边地表沉降及围护结构侧向位移进行了监测分析。结果表明:富水粉土粉砂地层中,落底式止水帷幕能有效隔断坑内和外部水力联系。群井抽水试验结束后,24h坑内水位恢复率在23.56%~54.73%;基坑开挖引起的地表沉降最大值在距基坑墙体8~10m处,基坑中部断面周围地表沉降大于基坑端部,坑角效应显著;地下连续墙最大侧向位移δ_(hm)为(0.03%~0.14%)H,均值约为0.09%H,最大侧向位移发生位置在开挖底面以上8m深度处;富水粉土粉砂地层地下水丰富,有多层承压含水层,且各含水层之间具有一定水力联系。研究成果可为相似地区基坑工程提供参考。In order to investigate the changes of the peripheral seepage and displacement fields induced by deep foundation pit descending excavation in water-rich chalky soil and chalky sand strata in Tianjin,a pumping test was carried out with a deep foundation pit in a Metro station in Tianjin as the engineering background,and the groundwater level outside the pit,surface settlement around the pit and lateral displacement of the enclosing structure were monitored and analyzed during the excavation stage.The results show that in the water-rich silty soil formation,the drop-bottom water stopping curtain can effectively isolate the hydraulic connection between the pit and the outside.After the end of the group well pumping tests,the recovery rate of the water level in the pit in 24 hours is in the range of 23.56%~54.73%.The maximum value of surface settlement caused by the excavation of the foundation pit is in the distance of 8~10m from the wall of the foundation pit,and the surface settlement around the section in the middle of the pit is greater than that at the end of the pit,and the pit corner effect is significant.The maximum lateral displacement of the diaphragm wallδ_(hm) is in the range of(0.03%~0.14%)H,with an average value about 0.09%H.The maximum lateral displacement is at the depth of 8m above the excavation bottom.The water-rich silty layer is rich in groundwater,with multiple layers of pressurized aquifers,and there are the hydraulic connections between the aquifers.The study results can provide the reference for foundation pit projects in similar areas.

关 键 词：基坑工程 基坑变形 地下水变化 富水粉土粉砂地层 现场监测 

分 类 号：TU43[建筑科学—岩土工程]